Our objective is to gain a better understanding of neural encoding in the auditory system as it pertains to animal communication by sound. Quantitative electrophysiology coupled with behavioral experimentation forms the core of our approach. Immediate goals are 1) to gain a quantitative understanding of stimulus representation in the auditory periphery; 2) to describe the encoding of vocalizations in the auditory system of birds. Computer techniques and communication theory oriented models are employed throughout. A long term goal is that our findings will lead us to the identification of principles of neural encoding which can be extended to the neural processing of speech in humans. BIBLIOGRAPHIC REFERENCES: Sachs, M. B., Linear and nonlinear aspects of auditory-nerve fiber discharge patterns, Proc. of the Vth International Biophysics Congress, Copehagen: 18 (1975). Abbas, P. J. and Sachs, M. B., Two-tone suppression in auditory-nerve fibers: Extension of a stimulus-response relationship, J. Acoust. Soc. Amer. (in press) (1975).